Operative Management of Chronic Unreduced Knee and Proximal Tibiofibular Dislocations

INTRODUCTION AND PATHOANATOMY

Acute dislocation of the knee is universally recognized as a true orthopedic emergency, primarily due to the high incidence of concomitant vascular damage—specifically to the popliteal artery, which is firmly tethered proximally at the adductor hiatus and distally at the soleus arch. Because of the limb-threatening nature of acute multiligamentous knee injuries (MLKI), prompt closed or open reduction is the standard of care. Consequently, old, unreduced dislocations of the knee are exceedingly rare in modern orthopedic practice, typically presenting only in cases of severe polytrauma, delayed medical presentation in developing regions, or missed diagnoses in obtunded patients.

When a knee dislocation is left unreduced, the pathoanatomy undergoes profound and irreversible changes. The joint space becomes obliterated by dense, organized fibrous tissue. Even if the articular cartilage appears macroscopically normal upon initial surgical exposure, the lack of synovial fluid circulation and the presence of chronic mechanical pressure inevitably lead to chondrocyte apoptosis and cartilage degradation. Furthermore, dense adhesions develop between the articular surfaces, the joint capsule contracts severely, and the collateral and cruciate ligaments scar into non-functional, shortened configurations.

💡 CLINICAL PEARL: The Illusion of Normal Cartilage

In chronic dislocations, articular cartilage may initially appear pristine and glistening upon arthrotomy. However, surgeons must be aware that prolonged immobilization and lack of physiological loading compromise the structural integrity of the chondral matrix. A useful range of motion (ROM) is seldom restored after open reduction alone due to the rapid reformation of adhesions and underlying chondromalacia.

Despite these challenges, satisfactory functional results have been reported following open reduction performed up to 4 months post-injury. In extreme cases of chronicity, such as a reported 40-year unreduced dislocation, gradual reduction utilizing circular external fixation (the Ilizarov method) has been successfully employed to mitigate the risk of acute neurovascular traction injuries.

PREOPERATIVE EVALUATION AND DECISION MAKING

The management of a chronic knee dislocation requires a multidisciplinary approach and exhaustive preoperative planning.

Vascular and Neurological Assessment

• Vascular Status: The popliteal artery may have formed collaterals or may be encased in dense scar tissue. A preoperative CT angiogram (CTA) or conventional arteriogram is mandatory to map the vascular tree.
• Neurological Status: The common peroneal nerve (CPN) is highly susceptible to injury, particularly in posterolateral dislocations. Baseline electromyography (EMG) and nerve conduction studies (NCS) should be obtained if a deficit is present.

Surgical Indications

The decision matrix for a chronic unreduced knee dislocation hinges on the condition of the articular cartilage, the patient's age, and their functional demands:
1. Open Reduction and Ligamentous Reconstruction: Indicated for younger patients with viable articular cartilage and a dislocation of relatively short duration (< 4 months).
2. Gradual Reduction (Ilizarov Device): Indicated for severe, long-standing chronic dislocations where acute open reduction would cause catastrophic stretching of the neurovascular bundle.
3. Arthrodesis (Joint Fusion): The gold standard for young, high-demand laborers with irreversibly damaged cartilage.
4. Total Knee Arthroplasty (TKA): Reserved for older, lower-demand patients. This typically requires a rotating-hinge prosthesis due to the complete absence of ligamentous competence.

SURGICAL MANAGEMENT OF OLD UNREDUCED KNEE DISLOCATIONS

The following technique describes the comprehensive open reduction of a chronically dislocated tibiofemoral joint.

🔪 SURGICAL TECHNIQUE 61-2: Open Reduction of Chronic Knee Dislocation

1. Patient Positioning and Setup

• Place the patient supine on a radiolucent operating table.
• Apply a high thigh tourniquet, but inflate it only if necessary, as prolonged ischemia in a potentially compromised vascular bed should be minimized.
• Prepare and drape the limb to allow full manipulation of the hip, knee, and ankle. Ensure a sterile tourniquet is available if proximal extension of the incision is required.

2. Surgical Approach

• Utilize an anteromedial parapatellar approach to gain extensive exposure of the knee joint.
• If the patella has been chronically displaced (either medially or laterally), tailor the skin incision to correspond with the normal anatomical location of the medial borders of the quadriceps tendon, the patella, and the patellar tendon. This ensures that once the joint is reduced, the skin closure will not be subjected to excessive tension over bony prominences.

3. Deep Dissection and Soft Tissue Release

• Perform a meticulous arthrotomy. You will immediately encounter dense, unyielding fibrous tissue obliterating the gutters and the intercondylar notch.
• Begin excising this fibrous tissue systematically to expose the articular surfaces completely.
• Subperiosteal Dissection: To mobilize the chronically displaced tibia and femur, it is often necessary to dissect the soft structures subperiosteally from the posterior aspect of both the femur and the tibia.
• Surgical Warning: Extreme caution must be exercised during posterior subperiosteal elevation. The popliteal artery and vein are frequently scarred down to the posterior capsule. Keep the dissection strictly on the bone (subperiosteal plane) to avoid catastrophic vascular injury.

4. Joint Assessment and Reduction

• Once the distal femur and proximal tibia are mobilized, assess the articular cartilage.
• Scenario A (Cartilage Undamaged): If the cartilage appears viable, gently reduce the dislocation. This may require sequential releases of the posterior capsule, the medial collateral ligament (MCL), or the lateral collateral ligament (LCL). Avoid forceful levering, which can cause iatrogenic fractures of the osteopenic bone.
• Scenario B (Cartilage Irreversibly Damaged): If the cartilage is destroyed, eburnated, or severely fibrillated, open reduction alone will result in a painful, stiff joint. Proceed directly with arthrodesis of the knee (utilizing an intramedullary nail or dual-plate construct) if the patient is young and active.
• Scenario C (Arthroplasty Indicated): In older patients, if arthroplasty is the chosen definitive treatment, it is often prudent to perform the procedure in a staged manner. First, reduce the joint and stabilize it (often with a spanning external fixator), proceed with soft tissue rehabilitation and restoration of the neurovascular baseline, and perform the definitive hinged TKA at a later date.

MANAGEMENT OF PROXIMAL TIBIOFIBULAR JOINT DISLOCATIONS AND LATERAL RECONSTRUCTION

Chronic knee dislocations, particularly those involving posterolateral corner (PLC) injuries, often necessitate addressing the proximal tibiofibular joint. In cases where the proximal fibula is severely damaged, chronically dislocated, or when a proximal fibular graft is required, specific techniques must be employed to preserve lateral knee stability.

🔪 SURGICAL TECHNIQUE 61-1: Proximal Fibular Resection and Lateral Reconstruction

1. Anatomical Considerations and Approach

• The proximal tibiofibular joint is stabilized by the anterior and posterior superior tibiofibular ligaments, the biceps femoris tendon, and the fibular collateral ligament (FCL).
• The common peroneal nerve (CPN) is the most critical structure in this region. It courses posterior to the biceps femoris tendon, wraps around the fibular neck, and divides into the deep and superficial peroneal nerves.
• Make a lateral longitudinal incision centered over the fibular head, extending distally along the fibular shaft.

2. Nerve Identification and Protection

• Identify the CPN proximally beneath the posterior border of the biceps femoris.
• Perform a meticulous neurolysis, freeing the nerve from surrounding scar tissue. Retract it gently using a vessel loop. Never apply excessive traction to the CPN.

3. Subperiosteal Dissection

• The fibular dissection must be strictly subperiosteal. This is the most reliable method to prevent iatrogenic injury to the CPN and the anterior tibial artery, which passes through the interosseous membrane just distal to the fibular neck.
• Incise the periosteum longitudinally and use a periosteal elevator to strip the soft tissues circumferentially.

4. Preservation of the Fibular Styloid

• When removing a proximal fibular graft or resecting the fibular head for a chronic dislocation, it is absolutely critical that the lateral supporting structures of the knee joint be reconstructed.
• The Styloid Osteotomy: Accomplish this by performing an osteotomy at the base of the proximal fibular styloid process. Preserve this bony fragment along with its attached ligaments (the FCL and the biceps femoris tendon).
• Resect the necessary portion of the proximal fibula.

5. Lateral Reconstruction

• The preserved fibular styloid, with its attached FCL and biceps femoris, must now be securely anchored to the proximal lateral tibia to restore posterolateral stability.
• Prepare a bleeding bony bed on the lateral aspect of the tibial plateau (Gerdy's tubercle region).
• Fix the styloid process to the tibia using a cancellous lag screw with a spiked washer, or utilize heavy non-absorbable sutures passed through transosseous drill holes.
• Test the reconstruction by applying varus stress and assessing external rotation stability at 30 degrees of knee flexion.

POSTOPERATIVE CARE AND REHABILITATION

The postoperative management of chronic knee dislocations and proximal tibiofibular reconstructions is a delicate balance between protecting the surgical repair and preventing debilitating arthrofibrosis.

Immobilization Phase

• Immediately postoperatively, the limb is placed in a long leg, bent-knee cast or a rigid hinged knee brace locked at 30 degrees of flexion.
• Flexion at 30 degrees relaxes the posterior neurovascular structures, reduces tension on the popliteal artery, and minimizes stress on the newly reconstructed posterolateral structures.
• This immobilization is typically maintained for 6 weeks to allow for rigid biological healing of the capsular tissues and bony osteotomies.

⚠️ SURGICAL WARNING: Cast Application

When applying a long leg cast post-reconstruction, ensure meticulous padding over the fibular head and the common peroneal nerve. Postoperative swelling within a rigid cast can easily cause a compressive peroneal nerve palsy. Frequent neurovascular checks are mandatory in the first 48 hours.

Rehabilitation Phase

• Weeks 6 to 12: The cast is removed, and the patient is transitioned to a hinged knee brace. Progressive, protected weight-bearing is initiated.
• Aggressive physical therapy focuses on restoring the range of motion. However, because of the chronic nature of the initial injury, patients must be counseled that achieving full flexion is highly unlikely. A functional arc of motion (0 to 90 degrees) is considered a successful outcome.
• Months 3 to 6: Focus shifts to quadriceps and hamstring strengthening. The dynamic stabilizers of the knee must be optimized to compensate for any residual ligamentous laxity.
• Treatment thereafter should mirror the protocols described for acute injuries of the lateral knee ligaments, emphasizing proprioceptive training and gradual return to activities of daily living.

COMPLICATIONS AND PITFALLS

Surgeons undertaking the treatment of chronic knee dislocations must be prepared to manage significant complications:

1. Vascular Compromise: The highest risk occurs during posterior subperiosteal dissection or immediately following joint reduction. If distal pulses are lost or the Ankle-Brachial Index (ABI) drops below 0.9 post-reduction, immediate vascular surgery consultation and exploration are required.
2. Peroneal Nerve Palsy: Can occur from direct surgical trauma, traction during reduction, or postoperative swelling. Most traction neuropraxias resolve within 3 to 6 months, but complete transections or severe crush injuries carry a poor prognosis, often necessitating a subsequent ankle-foot orthosis (AFO) or tendon transfer (e.g., Bridle procedure).
3. Arthrofibrosis: The most common complication. Despite perfect surgical technique, the joint's propensity to form scar tissue is immense. Manipulation under anesthesia (MUA) or arthroscopic lysis of adhesions may be required if flexion fails to progress past 60 degrees by 12 weeks.
4. Advanced Osteoarthritis: Even with successful reduction, the prolonged period of abnormal joint mechanics guarantees the eventual onset of post-traumatic arthrosis. Patients must be educated preoperatively that the open reduction is often a joint-salvage procedure designed to delay, rather than prevent, the eventual need for arthrodesis or arthroplasty.